Privacy key in a wireless communication system
Core network equipment ( 20 ) in a wireless communication system transmits control plane signaling ( 22 ) to a user equipment ( 16 ) which receives that control plane signaling ( 22 ). The control plane signaling ( 22 ) indicates a privacy key ( 24 ) with which a subscriber identifier (e.g., an international mobile subscriber identity, IMSI) associated with the user equipment ( 16 ) is to be encrypted or decrypted. The control plane signaling ( 22 ) may be non-access stratum, NAS, signaling. The privacy key ( 24 ) may be a public key of a home network associated with the subscriber identifier.
1. A method performed by a user equipment in a wireless communication system, the method comprising:
receiving at the user equipment, from core network equipment, a 5G Non-Access Stratum (NAS) message in the form of a Registration Accept including a public key of a home network of the user equipment with which a subscriber identifier associated with the user equipment is to be encrypted by the user equipment;
in response to receiving the Registration Accept, transmitting acknowledgement information acknowledging reception of the Registration Accept;
storing the public key of the home network in an elementary file in a universal subscriber identification module in the user equipment;
encrypting the subscriber identifier for the user equipment using the public key of the home network; and
transmitting the subscriber identifier as encrypted by the public key of the home network.
2. The method of claim 1 , wherein Registration Accept is signaled according to a security context previously established between the user equipment and the core network equipment.
3. The method of claim 1 , wherein the Registration Accept is integrity protected and/or ciphered using a key shared between the user equipment and the core network equipment.
4. The method of claim 1 , wherein the subscriber identifier is a long-term subscriber identifier or a permanent subscriber identifier.
5. The method of claim 1 , wherein the subscriber identifier is or is a portion of an International Mobile Subscriber Identity (IMSI).
6. The method of claim 1 , wherein the subscriber identifier is a pseudonym identifier associated with a long-term subscriber identifier or a permanent subscriber identifier.
7. User equipment for use in a wireless communication system, the user equipment comprising:
processing circuitry and memory, the memory containing instructions executable by the processing circuitry whereby the user equipment is configured to:
receive at the user equipment, from core network equipment, a 5G Non-Access Stratum (NAS) message in the form of a Registration Accept including a public key of a home network of the user equipment with which public key of the home network a subscriber identifier associated with the user equipment is to be encrypted by the user equipment;
in response to receiving the Registration Accept, transmit acknowledgement information acknowledging reception of the Registration Accept;
store the public key of the home network in an elementary file in a universal subscriber identification module in the user equipment;
encrypt the subscriber identifier for the user equipment using the public key of the home network; and
transmit the subscriber identifier as encrypted by the public key of the home network.
8. The user equipment of claim 7 , wherein Registration Accept is signaled according to a security context previously established between the user equipment and the core network equipment.
9. The user equipment of claim 7 , wherein the Registration Accept is integrity protected and/or ciphered using a key shared between the user equipment and the core network equipment.
10. The user equipment of claim 7 , wherein the subscriber identifier is a long-term subscriber identifier or a permanent subscriber identifier.
11. The user equipment of claim 7 , wherein the subscriber identifier is or is a portion of an International Mobile Subscriber Identity (IMSI).
12. The user equipment of claim 7 , wherein the subscriber identifier is a pseudonym identifier associated with a long-term subscriber identifier or a permanent subscriber identifier.